Apron drafting systems

ABSTRACT

An apron drafting system for a spinning machine, in particular an air spinning machine, with a bottom apron guided over a drivable bottom roller, the bottom apron being supported in the area of a drawing zone, in particular a main drawing zone, by a sliding section of an apron bridge. In order to provide an apron drafting system in which reliable guidance of the bottom apron is ensured while maintaining a high drive power, there is provision for the apron bridge for guiding the bottom apron to have a line section with guiding means for lateral guidance of the bottom apron circulating around the apron bridge.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from German National Patent Application No. DE 102019110881.0, filed Apr. 26, 2019, entitled “Riemchenstreckwerk”, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an apron drafting system for a spinning machine, in particular an air spinning machine, with a bottom apron guided over a drivable bottom roller, the bottom apron being supported in the area of a drawing zone, in particular a main drawing zone, by a sliding section of an apron bridge.

BACKGROUND OF THE INVENTION

Drafting systems of various embodiments for spinning machines are known from the prior art. They are used to draft or draw a fiber band, in which case the cross-section of the fibers is reduced. During the drawing, the fibers must be slid next to each other as uniformly as possible so that a uniform fiber band is achieved, which is a prerequisite for producing a uniform yarn. In order to draft the fiber band, the drafting systems generally have a plurality of roller pairs arranged one after the other, which roller pairs, arranged lying on each other, clamp the fiber band running between them. A roller pair usually consists of a driven bottom roller and a top pressure roller lying on the bottom roller. Drawing of the fiber band is achieved in that the circumferential speed increases from roller pair to roller pair in the transporting direction of the fiber band defined by the direction of rotation of the roller pairs.

Since the fibers of the fiber bundle lose their cohesion, especially in the main drawing zone where the fiber band is drawn with high drawing values, drafting systems implemented as apron drafting systems of the type mentioned above have already been disclosed, in which the fiber band is passed through aprons between the clamping lines of the two drawing roller pairs. What are referred to as double apron drafting systems are particularly widespread in this context, in which one apron each is guided around a first top and bottom roller in the area of the main drawing zone and is deflected by a deflecting device from the fiber guidance direction towards the second roller pair into the return direction, so that the fiber band is guided between the top and bottom apron.

Usually, the aprons, which are configured as an endless band, are guided at least around the drivable bottom roller, a deflecting device and a tensioning apparatus which keeps the bottom apron at the pretension required for operation. The bottom apron can be driven via the drivable bottom roller, in which case the transmission of the drive torque from the roller to the apron is usually ensured by a frictional connection with a top apron or a top roller.

An essential factor in the yarn quality is the fiber guidance of the fiber band or the drawing quality, in which case a uniformly spun yarn is achieved by uniform drawing of the fiber band. Due to the main drawing in an apron drafting system in the area of the apron guide, perfect guidance in this area is of decisive importance. It has already been disclosed in European Patent Publication EP 2 034 060 that guidance is ensured by an apron tensioning apparatus with a tensioning arm and a weighting device. However, this apron tensioning apparatus has the disadvantage that it leads to a loss of drive power.

SUMMARY OF THE INVENTION

Based on this, the problem addressed by the present invention is that of providing an apron drafting system in which reliable guidance of the bottom apron is ensured while maintaining a high drive power.

The problem is solved by the present invention by an apron drafting system having the features as set forth herein.

Advantageous further developments of the present invention are also stated herein.

It is characteristic of the apron drafting system according to the present invention that the apron bridge for guiding the bottom apron has a line section with guiding means for lateral guidance of the bottom apron circulating around the apron bridge.

The bottom apron, which is guided around the drivable bottom roller, is supported by the apron bridge which prevents the bottom apron from diverting downwards, especially in the area of the main drawing zone. In the area of contact with a top roller or a top apron, the bottom apron is guided over a sliding section of the apron bridge on which the bottom apron is thus supported in the area of the drawing zone. According to the present invention, the apron bridge also has a line section which is provided with guiding means for the purpose of lateral guidance of the bottom apron circulating around the apron bridge. The guiding means ensure that the bottom apron is held so as to run centrally in an area deviating from the sliding section, so that the bottom apron is reliably prevented from running off to the side, which would lead to losses of quality in the yarn to be produced.

The configuration of the line section on the apron bridge allows additional components to be dispensed with, so that the apron drafting system can be manufactured particularly easily and cost-effectively. In addition, the guiding means guiding the bottom apron laterally ensure minimal friction, so that any loss of drive power is excluded or minimized.

The embodiment of the guiding means on the apron bridge also makes it possible to dispense with separate guiding devices which would increase the complexity of the apron drafting system. The apron drafting system according to the present invention is thus characterized by its simplicity and compactness, which makes it possible to ensure that the bottom apron circulates reliably even without a device for tensioning the bottom apron, in which case production tolerances of the bottom apron also do not negatively influence the functioning.

The embodiment of the guiding means for guiding the bottom apron is basically freely selectable. According to a particularly advantageous embodiment of the present invention, however, there is provision for the apron bridge to have two guide bars arranged at a distance from one another and laterally enclosing the bottom apron in the area of the line section.

The use of guide bars is characterized by the fact that they can be configured in a particularly simple way on the apron bridge. These are arranged in any area of the apron bridge in such a way that they laterally enclose a bottom apron circulating around the apron bridge and thus prevent the bottom apron from diverting to the side. The guide bars can, for example, be configured as one-piece pins configured with the apron bridge, the distance between them essentially corresponding to the width of the circulating bottom apron. The line section configured by means of the guide bars can be configured at any point on the apron bridge, in which case the particularly preferable arrangement is on an underside of the apron bridge opposite the sliding section in the return area of the bottom apron.

The embodiment of the guide bars is basically freely selectable. For example, these can be made of a special ceramic or plastic material which has a low coefficient of friction for the circulating bottom apron. According to a particularly advantageous embodiment of the present invention, however, there is provision for the guide bars to have a sliding coating in the area of contact with the bottom apron. This embodiment of the present invention makes it possible to implement the apron bridge with the guide bars independently of any sliding properties and then to adapt the guide bars optimally to the bottom apron by applying a suitable coating to the guide bars.

The guide bars can basically be connected directly to an underside of the apron bridge. According to a particularly advantageous embodiment of the present invention, however, there is provision for the guide bars to be arranged on a stabilizing bar which runs along an area of the apron bridge opposite the sliding section. The use of a stabilizing bar increases the strength of the apron bridge in a complementary way and thus particularly reliably ensures that the circulating bottom apron is sufficiently supported. Furthermore, the use of the stabilizing bar offers the possibility of a particularly reliable arrangement of the guide bars, thus ensuring reliable operation.

According to a further embodiment of the present invention, there is provision for adjustment of: a drafting system carriage with the bottom roller, the bottom apron and the apron bridge and/or the apron bridge in relation to the drafting system carriage, transversely to the circumferential direction of the bottom apron.

Since the bottom apron has to be pressed against a top apron or top roller, if there is one, for drafting a fiber band, in particular in the area of the main drawing zone, wear occurs on the surfaces in contact with the fiber bands as a result of friction. As wear progresses, the quality of the spun yarn is increasingly negatively influenced, which leads to considerable disadvantages, in particular in the case of high-drawing drafting systems, meaning that the aprons have to be replaced often.

The possibility of adjusting the apron bridge transversely to the circumferential direction of the bottom apron, as described in the further development of the present invention above, enables a traversing movement of the bottom apron transversely to the running direction of the fiber band. A traversing movement leads to uniform wear on the surface of the bottom apron and thus, compared to non-adjustable bottom aprons, ensures a consistently high quality of the produced yarn over a relatively long period of use of the bottom apron.

In the case of an adjustment movement of the apron bridge in relation to the drafting system carriage bearing it, the apron bridge is adjustably mounted in a corresponding manner on the drafting system carriage on which, among other things, the bottom roller and the bottom apron are arranged. An adjustment movement of the apron bridge transversely to the running direction of the fiber band can also be achieved by mounting the entire drafting system carriage on the apron drafting system in such a way that it can be adjusted transversely to the running direction of the fiber band.

The traversing movement of the apron bridge can also cause the rubbing effect on the fiber bundle, which has a positive influence on the tear resistance of the roving and the yarn because the individual fibers in the roving adopt a denser and less ordered position, so that the contact surfaces grow larger and the tensile strength of the roving also increases accordingly.

For an adjustment movement of the line section of the apron bridge for lateral adjustment of the bottom apron via the guiding means, on the one hand the apron bridge can be adjusted in relation to the drafting system carriage and/or the drafting system carriage of the drafting system can be adjusted in its entirety transversely to the running direction of the fiber band. According to an advantageous further development of the present invention, there is provision for the apron bridge and/or the drafting system carriage to be connected to an adjusting drive for adjustment of the apron bridge in relation to the drafting system carriage and/or of the drafting system carriage transversely to the circumferential direction of the bottom apron.

The adjusting drive can thus be used for a convenient adjustment of the apron bridge in relation to the drafting system carriage or of the drafting system carriage in relation to the apron drafting system, so that the bottom apron is moved laterally back and forth by shifting the line section. The use of an adjusting drive allows the traversing speed, which is decisive for the quality of the method, to be optimally adapted to the fiber band to be drafted. In this way, an excessively high traversing speed, which leads to a reduction in the strength of the roving, can be reliably avoided, while in addition to the traversing speed, the traversing breadth, which is also decisive for the quality of the method, can also be reliably defined via the adjusting drive.

The adjusting drive thus permits optimal adaptation of the traversing breadth and traversing speed, so that no losses of quality occur in the roving, while at the same time wear on the bottom apron is significantly reduced compared to a traversing movement that does not take place.

According to a particularly advantageous embodiment of the present invention, there is provision for the adjusting drive to be connected to a control device for defining the adjustment movement of the drafting system carriage and/or the apron bridge, in particular for defining the adjustment length and the adjustment frequency.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings wherein:

FIG. 1 shows a perspective view of a roller pair arrangement of an apron drafting system according to an embodiment example;

FIG. 2 shows a perspective view of a drafting system carriage of the apron drafting system of FIG. 1 according to an embodiment example;

FIG. 3 shows a perspective view of an apron bridge of the drafting system carriage of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the embodiments of the present invention is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. The following description is provided herein solely by way of example for purposes of providing an enabling disclosure of the invention, but does not limit the scope or substance of the invention.

FIG. 1 depicts a perspective representation of a roller pair arrangement 1 of an apron drafting system which can be assigned to a spinning position (not depicted here) of a textile machine, which apron drafting system can be fixed to the textile machine. The roller pair arrangement 1 has four first to fourth top rollers 23, 24, 25, 26 arranged one behind the other in the running direction of a fiber band not depicted here running through the roller pair arrangement 1, which are opposite corresponding, drivable first to fourth bottom rollers 3, 4, 5, 6. The first to fourth bottom rollers 3, 4, 5, 6 include the infeed roller 3, which is the first to come into contact with the fiber band, can be driven by a roller drive and represents the first bottom roller of the roller pair arrangement 1. The infeed roller 3 can be arranged together with the roller drive on a first drafting system carriage 8 a.

A first drawing roller 4 is installed downstream of the infeed roller 3 in the fiber band running direction and is arranged on a second drafting system carriage 8 b. A second drawing roller 5 follows the drawing roller 4 in the fiber band running direction and is arranged on a third drafting system carriage 8 c. The first 4 and second drawing roller 5 can each be coupled with their own roller drive, which can also be arranged on the corresponding second 8 b or third drafting system carriage 8 c.

The second drawing roller 5 does not come into direct contact with a fiber band to be drawn, but has a bottom apron 10 circulating around the drawing roller 5 and coming into contact with the fiber band. The bottom apron 10 is implemented as an endless band and, in addition to the second drawing roller 5, also circulates around an apron bridge 9 arranged on supports 11 a, 11 b of the third drafting system carriage 8 c, in which case the supports 11 a, 11 b are arranged on a basic body 17. In the area of the third drafting system carriage 8 c, the bottom apron 10 rests against a sliding section 22 of the apron bridge 9 facing the bottom apron 10. The bottom apron 10 is supported via the sliding section 22, so that the bottom apron 10 cannot divert in the direction of the third drafting system carriage 8 c (see FIGS. 2 and 3).

On the side opposite the sliding section 22, the apron bridge 9 has two guide bars 13 which project at a distance from one another from an underside and form a line section 18, which rest against the side of the bottom apron 10 and serve as guiding means for the bottom apron 10. The guide bars 13 are in contact with a bar 12 arranged on the underside in the longitudinal axis direction of the apron bridge 9, which stabilizes the apron bridge 9.

The apron bridge 9 itself is moveably mounted on the support 11 a and in a receptacle 14 of the support 11 b, so that the apron bridge 9 can be adjusted transversely to the fiber running direction or to the running direction of the bottom apron 10 via an adjusting drive (not depicted here) for the apron bridge 9. A traversing movement of the bottom apron 10 can thus be performed via the guide bars 13 resting against the bottom apron 10, in which case a control device (not depicted here) connected to the actuating drive defines the traversing speed as well as the traversing breadth.

The fiber band drafted in the roller pair arrangement 1 passes over an outfeed roller 6, which is arranged on a fourth drafting system carriage 8 d, into a spinning unit (not depicted here), which follows the drafting system 1. The first to fourth drafting system carriages 8 a, 8 b, 8 c, 8 d can be arranged on a frame (not depicted) of the apron drafting system by means of suitable attachment points.

In an embodiment example not depicted here, an adjustment of the third drafting system carriage 8 c transversely to the circulating direction of the bottom apron 10 or the fiber running direction is provided in addition to or as an alternative to the adjustment of the apron bridge 9 in relation to the third drafting system carriage 8 c. The adjustment of the third drafting system carriage 8 c can be carried out by means of an adjusting drive according to a preferable embodiment example, in which case the adjustment of the third drafting system carriage 8 c can ideally be guided via at least one slot and a guide element projecting into it. In this way, a slot that can be provided in the drafting system carriage for fine adjustment of its position can be used in a simple manner for the traversing movement of the drafting system carriage. Drafting system carriages configured in this manner can therefore be used for an apron drafting system either with or without a traversing movement of the bottom apron. In order to improve the guiding stability, more than one slot can be provided in a particularly preferable embodiment.

In a further embodiment example not depicted here, the bottom apron is arranged in the same or a similar way in what is referred to as a pre-drawing field in addition to or as an alternative to the arrangement depicted in a main drawing field, this pre-drawing field being located upstream of the main drawing field in the transporting direction of the fiber band and being configured between two roller pairs lying in the transporting direction of the fiber band, which have rotational speeds that differ from one another. In this case too, traversing of the bottom apron can be carried out in a further preferable manner in the same or a similar way.

LIST OF REFERENCE SIGNS

-   -   1 Roller pair arrangement     -   3 Infeed roller     -   4 First drawing roller     -   5 Second drawing roller     -   6 Outfeed roller     -   8 a First drafting system carriage (for the infeed roller)     -   8 b Second drafting system carriage (for the first drawing         roller)     -   8 c Third drafting system carriage (for the second drawing         roller)     -   8 d Fourth drafting system carriage (for the outfeed roller)     -   9 Apron bridge     -   10 Bottom apron     -   11 a Support     -   11 b Support     -   12 Bar     -   13 Guide bar (guiding means)     -   14 Receptacle     -   17 Basic body     -   18 Line section     -   22 Sliding section     -   23 First top roller     -   24 Second top roller     -   25 Third top roller     -   26 Fourth top roller

It will therefore be readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many embodiments and adaptations of the present invention other than those herein described, as well as many variations, modifications and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing description thereof, without departing from the substance or scope of the present invention. Accordingly, while the present invention has been described herein in detail in relation to its preferred embodiment, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended or to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications and equivalent arrangements. 

What is claimed is:
 1. An apron drafting system for a spinning machine with a bottom apron guided over a drivable bottom roller, the bottom apron being supported in the area of a drawing zone by a sliding section of an apron bridge, characterized in that the apron bridge for guiding the bottom apron has a line section with a guide for lateral guidance of the bottom apron circulating around the apron bridge.
 2. The apron drafting system according to claim 1, wherein the spinning machine is an air spinning machine.
 3. The apron drafting system according to claim 1, wherein the drawing zone is a main drawing zone.
 4. The apron drafting system according to claim 1, characterized in that the apron bridge has two guide bars arranged at a distance from one another and laterally enclosing the bottom apron in the area of the line section.
 5. The apron drafting system according to claim 1, characterized in that the guide bars have a sliding coating in the area of contact with the bottom apron.
 6. The apron drafting system according to claim 1, characterized in that the guide bars are arranged on a stabilizing bar which is arranged in an area of the apron bridge opposite the sliding section.
 7. The apron drafting system according to claim 1, characterized in that adjustment of a drafting system carriage with the bottom roller, the bottom apron and the apron bridge and/or the apron bridge in relation to the drafting system carriage, is transverse to the circumferential direction of the bottom apron.
 8. The apron drafting system according to claim 7, characterized in that the apron bridge and/or the drafting system carriage is connected to an adjusting drive for adjustment of the apron bridge in relation to the drafting system carriage and/or of the drafting system carriage transversely to the circumferential direction of the bottom apron.
 9. The apron drafting system according to claim 1, characterized in that the adjusting drive is connected to a control device for defining the adjustment movement of the drafting system carriage and/or the apron bridge.
 10. The apron drafting system according to claim 9, wherein the adjusting drive is connected to a control device for defining the adjustment length and the adjustment frequency. 